Too Far, Too Fast

3M shares have been on a tear that could be about to end

FOR MUCH OF THE PAST TWO YEARS, 3M, which makes everything from sandpaper, Scotch tape, Scotchgard and Post-it Notes to fabric protectors, enhanced computer screens, automotive products and a cream for genital warts, has been the stock of choice for investors seeking shelter from a volatile equity market and uncertain economy. But the shares' sharp rise -- last month, they hit a record 145.70 -- has led some to scribble "Sell" or "Lighten Up" on their mental Post-its.